Reception of wireless signals



Oct. 6, 1925.

H. J. ROUND RECEPTION OF WIRELESS SIGNALS Filed July 9, 1921 1 2 Sheets-Sheet 1 g mica/725?? l Alll vwemtoz HENRY J. ROUND. "W 20% 44 4/ Get. 6, 1925- H. J. ROUND R ECEPTION OF WIRELESS SIGNALS Filed July 9, 1921 2 Sheets-Sheet 2 l/E 75/200 YNE INVENTOR HENRY J. ROUND Y ATTORNEY Patented Oct. 6, 1925.

UNITED STATES PATENT OFFICE.

HENRY JOSEPH ROUND OF LONDON, ENGLAND, ASSIGNOB TO RADIO CORPORATION 01E AMERICA, A CORPORATION OF DELAWARE.

RECEPTION OF WIRELESS SIGNALS.

Application filed July 9,

To all whom it may concern:

Be it known that I, HENRY J OSEPH ROUND,

a British subject, and a resident of London,

England, have invented certain new and use- 5 ful Improvements in the Reception of Wireless Signals, of which the following is a specification accompanied by drawings.

This invention relates to an improved method of and apparatus for receiving wireless signals so that as little interference as possible may be experienced either from atmospheric or jamming waves.

It has been found experimentally that by employing more and more resonance the effect of atmospherics in particular can be much reduced, provided the resonance circuits employed give constant damping independent of the amplitude. The best possible effects are not usually obtained with any of the Well known valve methods of producing low damping unless an excessive number of valves is used. Particularly is this true when many thousands of oscillations are being summed up. Valve reaction circuits when arranged in the .well known ways for negativing damping have the serious defect that the negative resistance applied 1s a function of the amplitude, and in consequence when two signals arrive together summation of signals is altered and reading is rendered difficult.

According to this invention I employ a heterodyne to produce heat tones, and I pass these beat tone currents through resonance circuits built up of air condensers and of large amounts of copper. Now if the beat tones produced are n times the wave length of the original signal and the damping of the low resistance beat tone circuit is a value the tuning effect on the signal is as though a'circuit for the original signal had been produced with a damping This low be neglected and at the same time eddy cur- 1921. Serial N0. 483,492.

rent losses in the copper coils are not excessive so that the damping constant can be economically kept low. I can thus arrange for an effective damping as low as .00001 and constant over a large range of amplitude. Such a damping necessitates extraordinary constancy in the transmitter for full resonance effects to be obtained, but I have found this to be perfectly practicable. Owing to low damping, however, the Morse characters are smoothed off so much that it IS impossible to read the signals by car if the method is empkiyed really effectively and in consequence employ a recording apparatus comprising a siphon or undulator which will give a graph of the amplitude.

. The copper coils on account of their large size are liable to pick up signals and Xs and should therefore be completely shielded.

The invention is illustrated b the accompanying drawings, in which ig. 1 shows one embodiment of my invention; Figs. 2, 3, 4 and 5 are curves explaining the operation of my invention and Fig. 6 illustrates a modification thereof. 1

In Figure 1, A isthe receiving aerial, B an intermediate circuit by which the incoming signals are led to the grid circuit of a high frequency amplifier and rectifier'C to which circuit are led also oscillations from a heterodyne D. The beat currents in the anode circuit of C are led to resonance circuits E and F built up of air condensers and a large amount of copper so as to give extremely low damping. The beat currents then pass through amplifying valves G H I to a. rectifier J and the direct current is amplified by valves K L and actuates a re corder M. Earthed screening boxes indicated by dotted lines are provided for all the apparatus. If two different wave lengths are employed dots being given by one wave and dashes by the other, parts E to L are duplicated, the anode circuit of C being coupled to the two circuits E one of which is tuned to the one beat frequency and the other to the other, and the currents from the two valves L are led to a siphon recorder in opposite directions as shown in Fig. 6.

Figures 2, 3, 4, and 5, represent the effect in a receiver due to the transmission of the letters A, B, C, in the Morse code, two different wave lengths being employed, dots being given on one wave len th and dashes on the other. The parts alcove the lines represent dots and the parts below the lines dashes.

Figure 2. shows the efiect when no supertuning is employed, Figure 3 the efi'ect when there is a small amount of supertuning, and Figure 4 the effect when there is a large amount of supertuning. Under these circumstances it would be difficult if not impossible to interpret. the message by ear. Figure 5 shows a record made by a siphon recorder which has smoothed out the cor ners appearing in Figure 4.

Having now particularly described my' said invention what ll claim is 1. The method of heat reception of wire-' 'rents to actuate a recorder.

2. The method reception of wireless telegraph signals Which consists in converting the received high frequency oscillations to currents of a frequency above 3,000 cycles,

passing said currents through resonant circuits of damping so low that the signals cannot be detected by the ear, rectifying the said currents and causing the rectified currents to actuate a recorder,

3. The method of Wireless telegraph signaling which consists in sending the dots and dashes of the Morse code on two different wave lengths, obtaining two beat fre-v quencies above 3,000 cycles at the receiving station, passing the beat currents of each frequency through separate resonance circuits of damping so low that the signals cannot be detected by the ear rectifying the beat currents and causing the rectified currents to actuate a recorder.

4. In apparatus for receiving high frequency oscillations, a receiver of oscillations adapted to convert said oscillations to a beat frequency above 3,000-cycles, a rectifier, resonance circuits following said rectifier having a low damping constant for said beat frequency, means for rectifying said heat frequencies and a recorder adapted to be operated by said rectified currents.

HENRY JOSEPH ROUND. 

